ARM: omap3evm: enable VBUS switch for EHCI tranceiver

This was chosen by following the trace on the schematic from component U131
and U134 to the CPEN pin on the USB3320 device.

TWL4030.GPIO2-...->(T2_GPIO2_3V3)U131-..>nUSB2_EN-..>U134-..>EXP_nUSB2_1V8
which starts EHCI tranceiver USB3320.

This will set TWL4030.GPIO2 as output pin to drive EHCI tranceiver.

Signed-off-by: Zumeng Chen <zumeng.chen@windriver.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>